Supercritical CO2-induced New Chemical Bond of C-O-Si in Graphdiyne to Achieve Robust Room-Temperature Ferromagnetism

The realization of ferromagnetic ordering of two-dimensional (2D) carbon material graphdiyne (GDY) has attracted great attention due to its promising application in spin semiconductor devices. However, the absence of localized spins makes the pristine GDY intrinsically nonferromagnetic. Herein, we report the realization of robust room-temperature (RT) ferromagnetism (FM) with Curie temperature (T-C) up to 325 K for GDY Nanosheets (GDYNs) by supercritical CO2 (SC CO2). Experimental and theoretical calculations reveal that the new chemical bond of C-O-Si can be formed because of the unique effect of SC CO2, which help to enhance the charge transfer and generates long-range ferromagnetic order. The RT saturation magnetization (M-S) reaches 1.125 emu/g, which is much higher than that of carbon-based materials reported up to now. Meanwhile, by changing the conditions of SC CO2 such as pressure, ferromagnetic responses can be manipulated, which is great for potential spintronics applications of GDY.